Light-Emitting Device, Light-Emitting Apparatus, Electronic Device, and Lighting Device

Abstract

Provided is an inexpensive light-emitting device with high emission efficiency. Provided is a light-emitting device including an anode, a cathode, an EL layer positioned between the anode and the cathode; the EL layer includes a hole-transport region, a light-emitting layer, and an electron-transport region; the hole-transport region is positioned between the anode and the light-emitting layer; the electron-transport region is positioned between the cathode and the light-emitting layer; the hole-transport region contains any one of a sulfonic acid compound, a fluorine compound, and a metal oxide; the electron-transport region contains an organic compound having an electron-transport property; and an ordinary refractive index of the organic compound having an electron-transport property with respect to light with a wavelength greater than or equal to 455 nm and less than or equal to 465 nm is higher than or equal to 1.50 and lower than or equal to 1.75.

1 - 3 . (canceled) 
     
     
         4 . A light-emitting device comprising:
 an anode;   a cathode; and   an EL layer positioned between the anode and the cathode,   wherein the EL layer comprises a hole-transport region, a light-emitting layer, and an electron-transport region,   wherein the hole-transport region is positioned between the anode and the light-emitting layer,   wherein the electron-transport region is positioned between the cathode and the light-emitting layer,   wherein the hole-transport region comprises any one of a sulfonic acid compound, a fluorine compound, and a metal oxide,   wherein the electron-transport region comprises an organic compound having an electron-transport property, and   wherein an ordinary refractive index of the organic compound having an electron-transport property with respect to light with a wavelength greater than or equal to 455 nm and less than or equal to 465 nm is higher than or equal to 1.50 and lower than or equal to 1.75.   
     
     
         5 . A light-emitting device comprising:
 an anode;   a cathode; and   an EL layer positioned between the anode and the cathode, wherein the EL layer comprises a hole-transport region, a light-emitting layer, and an electron-transport region,   wherein the hole-transport region is positioned between the anode and the light-emitting layer,   wherein the electron-transport region is positioned between the cathode and the light-emitting layer,   wherein the hole-transport region comprises any one of a sulfonic acid compound, a fluorine compound, and a metal oxide,   wherein the electron-transport region comprises an organic compound having an electron-transport property, and   wherein an ordinary refractive index of the organic compound having an electron-transport property with respect to light with a wavelength of 633 nm is higher than or equal to 1.45 and lower than or equal to 1.70.   
     
     
         6 . The light-emitting device according to  claim 4 ,
 wherein a signal is detected at around m/z = 80 in a negative-mode measurement result of ToF-SIMS measurement in the hole-transport region.   
     
     
         7 . The light-emitting device according to  claim 5 , 
 wherein the hole-transport region has a signal at around m/z = 80 in a negative-mode measurement result of ToF-SIMS measurement.   
     
     
         8 . The light-emitting device according to  claim 6 , 
 wherein signals are detected at around m/z = 80 and at around m/z = 901 in a negative-mode measurement result of ToF-SIMS measurement in the hole-transport region.   
     
     
         9 . The light-emitting device according to  claim 4 , 
 wherein a signal is detected at around m/z = 80 in a negative-mode measurement result of MS analysis in the hole-transport region.   
     
     
         10 . The light-emitting device according to  claim 5 , 
 wherein the hole-transport region has a signal at around m/z = 80 in a negative-mode measurement result of MS analysis.   
     
     
         11 . The light-emitting device according to  claim 9 , 
 wherein a signal is detected at a mass number that is 241, 161, or 81 less than that in a mass range ±2.0 of a target ion in a negative mode of MS analysis in the hole-transport region.   
     
     
         12 . The light-emitting device according to  claim 4 , 
 wherein the hole-injection layer has a signal at a g-value of around approximately 2.00 in a measurement of electron spin resonance spectrum by an ESR method.   
     
     
         13 . The light-emitting device according to  claim 4 , 
 wherein the light-emitting layer comprises an iridium complex.   
     
     
         14 . The light-emitting device according to  claim 13 , 
 wherein the iridium complex emits green phosphorescent light.   
     
     
         15 . The light-emitting device according to  claim 13 , 
 wherein the light-emitting layer has a signal at around m/z = 1676 in a positive-mode measurement result of ToF-SIMS analysis.   
     
     
         16 . The light-emitting device according to  claim 13 , wherein the iridium complex is an iridium complex represented by a structural formula shown below
                       .   
     
     
         17 . The light-emitting device according to  claim 4 , 
 wherein the organic compound having an electron-transport property comprises at least one six-membered heteroaromatic ring having nitrogen, two benzene rings, one or more of aromatic hydrocarbon rings having 6 to 14 carbon atoms, and a plurality of hydrocarbon groups forming bonds by sp3 hybrid orbitals, and wherein the total number of carbon atoms forming the bonds by the sp3 hybrid orbitals accounts for higher than or equal to 10 % and lower than or equal to 60 % of the total number of carbon atoms in molecules of the organic compound having an electron-transport property.   
     
     
         18 . The light-emitting device according to  claim 4 ,
 wherein the electron-transport region comprises an electron-transport layer and an electron-injection layer, and   wherein the electron-injection layer is provided in contact with the cathode, and the organic compound having an electron-transport property is comprised in the electron-transport layer.   
     
     
         19 . The light-emitting device according to  claim 18 , 
 wherein the electron-transport layer further comprises a metal complex of an alkali metal or an alkaline earth metal.   
     
     
         20 . The light-emitting device according to  claim 18 , 
 wherein the electron-transport layer comprises a metal complex of an alkali metal or an alkaline earth metal further comprising a ligand having an 8-quinolinolato structure.   
     
     
         21 . The light-emitting device according to  claim 19 , 
 wherein the metal complex of an alkali metal or an alkaline earth metal is a metal complex of lithium.   
     
     
         22 . The light-emitting device according to  claim 18 , 
 wherein the electron-injection layer has a signal at around m/z = 587 in a positive-mode or negative-mode measurement result of ToF-SIMS analysis.   
     
     
         23 . The light-emitting device according to  claim 18 , 
 wherein the electron-injection layer comprises a heteroaromatic compound.   
     
     
         24 . The light-emitting device according to  claim 23 , 
 wherein the heteroaromatic compound is 2-phenyl-9-[3-(9-phenyl-1,10-phenanthrolin-2-yl)phenyl]-1,10-phenanthroline.   
     
     
         25 . The light-emitting device according to  claim 18 , 
 wherein the electron-injection layer further comprises fluorine and sodium.   
     
     
         26 . The light-emitting device according to  claim 18 , 
 wherein the electron-injection layer comprises barium.   
     
     
         27 . A light-emitting apparatus comprising a plurality of the light-emitting devices according to  claim 4 ,
 wherein each of the plurality of light-emitting devices comprises at least a light-emitting device emitting red light and a light-emitting device emitting green light, and   wherein a light-emitting layer of the light-emitting device emitting red light and a light-emitting layer of the light-emitting device emitting green light comprise iridium.   
     
     
         28 . The light-emitting apparatus according to  claim 27 , 
 wherein light emitted from each of the light-emitting device emitting red light and the light-emitting device emitting green light is phosphorescent light.   
     
     
         29 . The light-emitting apparatus according to  claim 27 ,
 wherein each of the plurality of light-emitting devices further comprises a light-emitting device emitting blue light, and   wherein light obtained from the light-emitting device emitting blue light is fluorescent light.   
     
     
         30 . The light-emitting apparatus comprising a plurality of the light-emitting devices according to  claim 4 . 
     
     
         31 . A display device comprising the light-emitting apparatus according to  claim 27 . 
     
     
         32 . The light-emitting device according to  claim 4 , 
 wherein the hole-transport region comprises a layer formed by applying and baking varnish containing a sulfonic acid compound.   
     
     
         33 . The light-emitting device according to  claim 5 , 
 wherein the hole-transport region comprises a layer formed by applying and baking varnish containing a sulfonic acid compound.   
     
     
         34 . The light-emitting device according to  claim 32 , 
 wherein the hole-transport region comprises a layer formed by applying and baking varnish containing the sulfonic acid compound and a secondary amine compound.